It happened several times to me, that I gave an answer, that the asking user commented as very useful but is not even giving me an up-vote. Even after saying that an up-vote would be nice.
I'd like to keep track of those users. (i.e. this user, who got 28 answers on 17 question but has only 1 up-vote)

My idea: Mark users with the colors green, yellow or red, where green is for users I'd like to answer again, as they were very polite, while red is reserved for users, that really freaked me out, as they are never giving credit, where credit is due.
Users become "mark-able" as soon, as they can vote up.
Users can mark other users with a reputation of 100 or 200
The color will be show in the little box below their question (next to their accept rate).

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

I wouldn't call it friend list. more a hint to myself.
–
vikingosegundoSep 17 '10 at 2:51

2

@viking It doesn't really matter if you intend to use it the same way, it's the same feature request (a way to mark certain users so that they show up differently from other users when you come across them)
–
Michael MrozekSep 17 '10 at 2:59

a friend list, as described in the other post (... allow us to be able to follow the Questions and Answers that are posted by ...), is very different. I am talking of a personalized for of the accept rate.
–
vikingosegundoSep 17 '10 at 3:08

Don't worry about individual users who you feel aren't contributing. You also answered the question to help anyone else with the same problem, right?

Of course, if any particular user is annoying you in some way, at least enough that you remember them, you're free to not answer their questions in the future. Is this just one user for you? If so, that's not a problem.

With this particular user only having 75 rep, they're relatively new to the system. Someusers just rarely upvote.